The present invention relates to metal turning apparatus and more particularly to a portable special purpose lathe for machining the friction surfaces of brake drums and brake discs or for boring, facing and turning surfaces of other components, particularly automotive parts, such as flywheels, starters and generator armatures, alternator slip rings, small shafts and the like.
A search of the prior art failed to uncover any prior art references which disclose the special purpose lathe of the present invention. A number of patents were uncovered which disclose various types of metal turning machines, including special purpose lathes for turning brake drums and discs. The following is a listing of the patents uncovered during the aforementioned search:
______________________________________ U.S. Pat. No. Patentee Issue Year ______________________________________ 1,820,717 Wadell 1931 2,357,803 Barrett 1944 2,663,975 Barrett 1953 2,891,435 Billeter 1959 2,960,765 Barrett 1960 3,049,953 Barrett 1962 3,075,413 Healy et al 1963 3,221,578 Parsons et al 1965 3,555,940 Cooper 1971 3,691,880 Ratteree et al 1972 3,724,327 Gillberg 1973 3,871,066 Mitchell 1975 4,165,662 Besenbruch et al 1979 4,215,603 Jones 1980 4,253,359 Youden 1981 ______________________________________
U.S. Pat. Nos. 3,871,066 and 4,165,662 disclose lathe machines and attachments for turning or grinding the friction surfaces of either a brake drum or a brake disc. However, the machines disclosed in those patents are not adapted for rapid changeover from a configuration for machining brake drums to a configuration for machining brake discs.
U.S. Pat. Nos. 2,663,975; 2,960,765; and 3,049,953 to Barrett disclose portable brake drum lathes each having an automatic tool feed which is driven via a drive transmission from the spindle motor.
U.S. Pat. Nos. 3,221,578 and 4,253,359 disclose complex metal turning machine tools having programmable mechanisms for powering the tool drives or slides of the machine for compound movement of the tools. Because of their complexity, the machines of these patents are not particularly suited for use as special purpose lathes for turning brake drums, brake discs and other automotive components.
The conventional special purpose lathes for turning brake drums and discs described in the aforesaid patents, such as the compact portable machines taught by Barrett and others, employ either manual tool feeds or a combination of a manual cross-feed and an automatic tool feed operable parallel to the spindle axis. Typically, in such special purpose machines, the automatic tool feed mechanism is driven via a gear train or other transmission means from the main spindle motor and thus requires a spindle motor with a relatively large horsepower rating. In addition, as previously noted, the conventional special purpose lathes for machining brake and other automotive components are not readily convertible between arrangements for the machining of brake drums and brake discs.